#include <stdio.h>
#include <stdlib.h>

int main(int argc, char *argv[]) {
  int n, a, b;

  /*  Input is "a b" for some natural numbers a,b.
      The output is "n" where n is the number of the ordered
      pair (a,b) under the following 
      enumeration of the ordered pairs of nat. numbers:

      <x,y> before <w,z>  iff  (x+y < w+z) or (x+y==w+z and x<w) */

  if (argc != 3) {
    printf("\n Two arguments expected!  Exit.\n");
    return 1;
  }

  a = atoi(argv[1]);
  b = atoi(argv[2]);
    
  if (a < 0 || b < 0) {
    printf("\n Two natural numbers expected!  Exit.\n");
    return 2;
  }   
    
  if (a == 0 && b == 0) {
    n = 0;
  }
  else {
    n = (a+b)*(a+b+1)/2 + b;
  }

  printf(" n = %d\n", n);

  return 0;
}